Improvement in hot-air furnaces



C. L. PIERCE.

Hot-Air Furnaces.

w Patented Apri! 22,1873.

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AM P/ioroimmammc ca My. (assums Peacem) UNITED STATEs CHARLES L. PIERCE,OF NATIGK, MASSACHUSETTS.

IMPROVEMENT IN HOT-AIR FURNACES.

Specification forming part of Letters Patent No. 138,188, dated April1873; application filed December 28, 1872.

` Improved Hot-Air Furnace; and I do hereby declare the following to bea full, clear, and

exact description of the same, reference being had to the accompanyingdrawing forming a part of this specification.

My invention consists, first, in providing a double and perfectlyuniform return draft,

thereby greatly increasing the radiating capacity of the furnace anddistributing the heat equally over the entire radiating surfaces. Thisinsures great durability for the radiators, which can never be heatedred hot. It also consists in an arrangement of an annular register inrelation to the combustionchamber and smoke-fines, whereby the accumulation from the ilues and chamber may be readily transferred to theash-pit. It also consists in making the tunnel project over airchamber,and by its conical form reect the current of heated air back upon top ofthe furnace, thus more thoroughly heating said air before it ascends toits destination.

In the drawing, Figure l is a central vertical section; and Fig. 2 is ahorizontal section through the line a: cc of Fig. l.

A represents the ash-pit, B 'the grate, G the iire-pot, and D thecombustion-chamber, of a hot-air furnace. d is a damper in the center oftop plate of said combustion-chamber, which is connected by a rod, d1,to a crank-shaft, d2. This shaft is turned by a leveror otherwise toopen or close the damper. E is an annular chamber formed around{ire-pot, made open at the top and passing down to a space, E', thesurrounding wall of which is a frustum of a cone, to which is connectedthe lower ends of a series of vertical fines, F, which connect at thetop with an oblique or conical tunnel, G, that projects over furnace onevery side to receive them. This tunnel then connects with the up-draftchamber H leading to smoke-flue. I is the cold-air chamber between thewhole heating apparatus and the case. This discharges the air afterbeing heated'into the pipes J J which lead to the apartments to beheated. K is an annular register arranged in space E, and provided withsuitable device so that it may be turned by hand. This. allows anydeposit from the pipes F to be readily transferred to the pit, fromwhich it is removed with the ashes through door a'. In the tunnel is achamber, L, that receives the products of combustion, from which a greatp0rtion of the heat has already been abstracted, that resists theirimmediate outward passage, and that causes them to dwell for a timeuntil their depletion is more thoroughly effected.

The hot gases and products of combustion, whenever the draft through thedamper d is cut off, are carried down over irepot G, through chamber E,and into space F/ 5 thence they are forced up the flues F, down thetunnel Gr, and into chamber H, from which they are discharged. V

The cold air that enters chamber I is carried up against outer cylinderofthe chamber E, around the flues F, and against the sloping outer faceof tunnel G, from thence it is reiiected back upon the top plate offurnace, one of the hottest parts of the heating-surface. It then passesout through pipes J.

These iiues F afford a very great increase of heatingsurface to the air,cause a great uniformity in distribution thereto of the heat, andutilize a greater percentage of it, while the overlapping tunnel withits reecting-surface contributes also to the latter in no small degree.

Practical experiment with a furnace now in full operation demonstratesnot only the correctness of the theory embodied in this construction,but that its advantages are of the most palpable and practicalcharacter.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is*

l. The chamber E E opening at top into combustion-chamber D and arrangedabout re-pot, in combination with a series of radiating vertical ilues,F, placed at intervals around the air-chamber and leading to thesmoke-nue through chamber L, as and for the purpose described.

2. A annular combustion chamber, D, having damper d at the top andopening into chamber E, as and for the purpose set forth.

3. The annular register Kl combined with the chambers E and E and finesF, and so arranged in relation to them thatit will allow any depositfrom either to be transferred to the ash-pit beneath it, as set forth.

4. The tunnel G declined inwardly and 0bliquely downward toward thecenter of combustion-chamber and having the smoke-flue H extending tonear the bottom thereof, in combination with damper D, combustionchamberD, annular chambers E vE', and fines F, as described, to enable thedeposit from the tunnel to be readily emptied into the firepot.

DR. CHARLES L. PIERCE.

Witnesses W. W. HEMENWAY, J Sl. EAsTMAN, Jr.

